In conventional surgery, surgeons use their fingers to measure the softness/hardness of tissues. Using this type of palpation, surgeons can investigate hidden anatomical features of tissues. They can also distinguish between different types of tissues. For example, they can identify abnormal tissues (such as tumorous lumps), blood vessels, ureters, and bony or fatty tissues. However, current commercially available minimally invasive robotic surgery (MIRS) systems do not provide tactile feedback from the interaction between surgical tools and tissues.
Indeed, despite the superiority in many cases of MIRS over conventional open surgery techniques, it has a few unsolved shortcomings. One of them is the lack of haptic feedback to surgeons. Such haptic feedback relies on sensory feedback, which consists of both the kinesthetic and cutaneous tactile feedback streams. Haptic feedback, which occurs while surgical instruments are interacting with tissues, can lead to better MIRS. For instance, visual force feedback results in reduced suture breakage, lower forces, and decreased force inconsistencies in the da Vinci™ surgical system. Similarly, experimental tests have proved that the presence of direct force feedback significantly reduces the force applied by the da Vinci™ graspers to the grasped tissue. That reduced force was not sustainable after removing the force feedback.
Therefore, similarly to a human finger, a tactile sensor is required to measure: 1) the softness/hardness of contact tissue, 2) the contact distributed load interacting between surgical tools and tissues, and 3) the position of a concentrated load interacting between surgical tools and tissues. Also, surgical tool-tissue interactions take place in both static and dynamic loading conditions. In order to avoid tissue damage because of the excessive force applied to the tissue, and also in order to maintain contact stability between surgical tools and tissues, surgeons can use a sensor to measure the static contact force applied to tissues by surgical tools. In addition, tool-tissue interaction involves low rate changes because of the viscoelastic properties of tissues. For example, tissue relaxation happens very slowly. As a result, the tactile sensor must measure the above-mentioned parameters in both static and dynamic loading conditions.
Finally, minimally invasive robotic surgeries are frequently performed in the presence of electro-magnetic fields. Magnetic resonance imaging (MRI) devices induce strong electro-magnetic fields. Nowadays, during MIRS, these devices are in widespread use in surgical rooms for various types of applications. For example, surgeons widely use MRI to investigate the live organs during MIRS. As another example, in MIRS applications, surgeons also use them to guide the surgical instruments and to track the position of surgical tools inside the body. Similarly, radio frequency (RF) pulses are usually present in the surgical operating rooms. For example, RF coil of MRI devices is one of the sources for RF pulses. Therefore, performing tactile measurements with currently existing tactile sensors, which include electrical wires, are impossible in many MIRS operations. Electrical wires included in the conventional sensors, such as piezoelectric sensors, usually induce eddy current fields which disturb the MRI images. In other words, in MRI environment, the use of electronics is not practical. Therefore, the surgical robot as well as its components such as sensors must be MRI compatible. Thus it is crucial to develop sensors performing tactile measurements even with the electromagnetic interference present in the surgical operating rooms. Hence, there is a need for novel concept of tactile sensor with components that are insensitive to electromagnetic fields. This ability allows sensors to work within environments with strong electromagnetic fields. In addition, for some specific types of surgeries, the sensor should be electrically passive due to the safety concerns of introducing electrical currents into the body. For instance, in intracardiac surgeries, to avoid disrupting normal electrical activities in the heart, which is an electrically active environment, the sensor must be electrically passive. As a result, the tactile sensor must be MRI compatible and electrically passive.
Accordingly, there is a need in the industry to provide an improved system for sensing a mechanical property of a sample. An object of the present invention is therefore to provide such a system.